[Flang] Incorrect diagnostic on v_list in defined I/O

[DanielCChen]

Consider the following code

module m
    type base
        real(4), allocatable :: d1
    end type

    interface read(formatted)
        subroutine formattedRead (dtv, unit, iotype, v_list, iostat, iomsg)
        import base
            class (base), intent(inout) :: dtv
            integer, intent(in) :: unit
            character(*), intent(in) :: iotype
            integer, intent(in) :: v_list(2:)  !<-- this is legal
            integer, intent(out) :: iostat
            character(*), intent(inout) :: iomsg
        end subroutine
    end interface
end module

Flang currently issues an error as:

./t.f:12:36: error: Dummy argument 'v_list' of a defined input/output procedure must be deferred shape
              integer, intent(in) :: v_list(2:)  !<-- this is legal
                                     ^^^^^^

1. The code is valid.
2. The error message complains about "deferred shape" where the v_list is supposed to be "assumed-shape".

All ifort, gfortran and XLF compile the code successfully.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: Daniel Chen (DanielCChen)

Consider the following code ``` module m type base real(4), allocatable :: d1 end type

interface read(formatted)
    subroutine formattedRead (dtv, unit, iotype, v_list, iostat, iomsg)
    import base
        class (base), intent(inout) :: dtv
        integer, intent(in) :: unit
        character(*), intent(in) :: iotype
        integer, intent(in) :: v_list(2:)  !<-- this is legal
        integer, intent(out) :: iostat
        character(*), intent(inout) :: iomsg
    end subroutine
end interface

end module

Flang currently issues an error as:

./t.f:12:36: error: Dummy argument 'v_list' of a defined input/output procedure must be deferred shape
integer, intent(in) :: v_list(2:) !<-- this is legal
^^^^^^

1. The code is valid.
2. The error message complains about "deferred shape" where the `v_list` is supposed to be "assumed-shape". 

All ifort, gfortran and XLF compile the code successfully.
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